High pressure valve

ABSTRACT

High pressure valve having a valve cone (12) guided by a valve spindle (10) within a valve housing (1, 2), the sealing surface (13) of the valve cone engaging, in the closed position, an annular ridge (15) of hard metal constituting a valve seat, whereby the sealing surface (13) at least of the valve cone (12) is made of a soft metal, preferrably aluminum.

BACKGROUND OF THE INVENTION

The invention relates to a high pressure valve having a valve coneguided by a valve spindle within a valve housing, which valve cone inits closed position engages an annular ridge of hard metal, inparticular steel, consituting a valve seat.

Such valves make use of the plastic deformation to which the softsealing surface is subjected when engaging the hard metal seat, toensure a constant sealing effect of the valve over an extended period oftime. Such a valve has been described, for instance, in German laid-openpatent specification DE-A-1 190 756. In the known valves the valve coneis made of copper or of copper-plated or gold-plated steel, and ismounted on a conventional valve spindle, made, for instance, of steel.Such construction requires the separate manufacturing steps of assembly,and the plating of the valve cones, as the case may be.

Furthermore, steel spindles and valve cones made of steel have a highmass inertia which at periodic switching operations of the valve leadsto a dynamic pressure loss in the range of about 4-5 bar. Finally, suchcone/spindle structures are unsuited for actuation by an electromagnetas they are potentially subject to magnetization.

SUMMARY OF THE INVENTION

It is, therefore, an object of the invention to provide a high pressurevalve of the structure referred to in the introduction, which isextremely tight, is of a low mass inertia in a switching operation, andin which the spindle and the valve cone may be assembled in a simplemanner and may be actuated by an electromag-net. In accordance with theinvention, this object is accomplished by the valve cone, the sealingsurface and the valve spindle being an integral structure made ofaluminum, and by the valve being a pressure compensated high pressurevalve. In accordance with the invention, the dynamic mass of the valvespindle/valve cone structure and, hence--in a periodically switchedvalve--the dynamic pressure loss is reduced. Furthermore, themanufacture of the valve is simplified because of the one-piecestructure of the valve cone, the sealing surface, and the valve spindle.In addition, because of the non-magnetec property of aluminum, anadditional advantage is obtained, in that magnetization of thecone/spindle structure by an electromagnet used for actuating thespindle, is avoided. Magnetization does occur in known steel spindlesand results in additional dynamic pressure losses because of theattraction forces of the magnetized parts, and in disturbing inherentspindle movements which have not been completely understood.

In the pressure compensated valve structure in accordance with theinvention, the aluminum sealing surface is not pressed against the steelannular ridge at full operating pressure, rather, the pressure isgenerated entirely by the control force acting upon the spindle. It canbe seen that because of that, wear of the soft metal sealing surfaceover an extended time is substantially avoided.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be explained in more detail with reference to thedrawing which depicts a two-position, two-way valve in longitudinalsection, with the sealing arrangement in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The valve is provided with a two-part valve housing 1, 2, the upper part1 of which at 3 is threaded to the lower part 2. At its upper end theupper part 1 is provided with a terminal flange 4, and at its lower endit is provided with an external thread 5 having standardized outerdimensions, so that the upper part 1, together with the threaded-inlower part 2, may be screwed into a standardized threaded valvereceiving bore. A flange seal 6 assures a leak-proof seat of the valvein the threaded bore (not shown). Valves of this kind are also calledscrew-in cartridge valves (cartridge valves).

The lower part 2 of the housing has a lesser external diameter than theupper part 1 of the housing and in a screwed-in condition thusconstitutes a lower valve section 7 of reduced outer diameter at thelower end of which there is arranged an O-ring 8 positioned within anannular groove. This O-ring 8 serves as a circumferential seal of thelower section 7 in a reduced diameter bore section of the threaded bore(not shown) within which the valve is received.

The connection between the housing parts 1, 2 is sealed by a furtherO-ring 9.

The housing parts 1, 2 are permeated by a shoulder provided with aplurality of shoulders in which the valve spindle 10 is guided for axialmovement. The spindle 10 is provided, at its lower end, with a section11 of reduced diameter which is extending into a valve head of increaseddiameter. The upper margin of of the valve head 12 adjacent the section11 is obliquely shaped thus forming a truncated or frusto-conicalsurface 13 which imparts to the valve head the function of a valve cone.The head of the spindle, that is to say, the valve cone, is movablewithin a section 14 of increased inner diameter of the lower housingpart 2, and, with the truncated or frusto-conical surface 13 functioningas a sealing surface, it engages an annular ridge 15, in the closedposition of the valve. The annular ridge is formed by the transitionbetween the widened section 14 of the bore in which the valve cone ismoving, and the axial section of the bore in which the valve spindle 10is moving.

At its upper end the valve spindle 10 is provided with a flange 17retained by a clamping ring 16, which flange 17 arrests a spring 18 theother end of which is supported by the upper front surface of the lowerhousing part 2. In this manner, the valve spindle 10 is biased in anupward direction, so that the sealing surface 13 of the valve cone 12 ispressed against the annular ridge 15 of the lower housing part 2.Therefore, the annular valve gap between the sealing surface 13 and theannular ridge 15 is closed in the depicted idle position of the valve.

The pressure chamber 19 of the bore below the valve cone 12 forms one ofthe pressure connections of the valve, and the annular chamber 20 formedabove the annular gap in the area of the valve spindle section 11 ofreduced diameter is provided with two diametrically opposite radialbores 21, 22 which provide the other pressure connections of the valve.The pressure extant within the annular chamber 20 simultaneously effectsthe upper and the lower shoulder surfaces of the spindle section 11, andis thus balanced in its effect upon the spindle 10.

The pressure chamber 19 is connected to a counter pressure chamber 24 byway of a bore or conduit 23 permeating the valve cone 12 and the valvespindle 10. The counter pressure chamber 24 is formed by a bore sectionof increased diameter within the upper housing section 1 and occupiesthe entire upper end of the valve spindle 10 including the biasingarrangement 16-18. Thus, the pressure present at the valve connection 19is diverted to both sides of the valve spindle, and is equalized.

Because of the pressure compensation at the connections 19, 21, 22 noaxial force will act upon the spindle when the valve is subjected topressure acting in the flow-through direction. The force for closing thevalve is thus generated solely by the spring force of the biasing spring18.

For actuating the valve spindle, a bolt 25 acting upon the upper frontsurface of the spindle 10, is movably provided within the upper housingpart 1. The bolt 25 may be actuated, for instance, by an electromagnet(not shown).

For sealing the valve output connection 21, 22 relative to the pressurechambers 19, 24 there is provided a packing 26 which sealingly embracesthe spindle 10 in the lower housing part 2 in the area between theoutput connections 21 and 22 and the counter pressure chamber 24.

This structure corresponds to the conventional pressure compensatedtwo-position, two-way valves which are available as screw-in valvecartridges with standardized exterior dimensions.

In accordance with the invention, the entire structure of valve spindle10, valve cone 12 and sealing surface 13 is made of aluminum. Thesealing surface 13 is precision lathed.

In the sealing gap an aluminum sealing surface faces an annular ridge 15made of steel. During initial switching operations, the annular ridge 15will slightly emboss itself into the sealing surface 13 and provide foran excellent seal. Even after a long service and frequent switchingoperations the aluminum will not deform further, so that the excellentsealing effect is maintained over an extended period.

In an actual embodiment a maximum loss of pressure of 4 bar/24 h wasdetected at an operating pressure of 200 bar. The same pressure loss of4 bar/24 h was still detected after a long operating time involving200,000 switching operations.

The basic material used for the valve spindle 10 and for the valve cone12 was aluminum with a tensile strength of 340N/mm². Compared to steel,this material has a substantially lower specific mass and, hence,substantially lower inertia. The dynamic pressure loss in periodicswitching operations is thus reduced to 1-2 bar. It should be added,that because of its non-magnetic property, aluminum is not magnetized byan electromagnet required for the actuation of the spindle, wherebydisturbance effects hitherto occurring in steel spindles duringswitching operations and not wholly explainable, are avoided.

Furthermore, it can be seen that in the depicted embodiment the valvespindle 10 may be removed in a downward direction and replaced afterremoval of the clamping ring 16. This has not been possible with steelvalve cones and steel sealing surfaces hitherto used, because the valveseat was optimized by forcibly jamming the valve cone 12 into theannular ridge valve seat 15, whereby the sealing surface 13 of hardenedsteel formed an downwardly directed flange in the annular ridge 15 whichrendered removal of the valve spindle impossible.

It will be appreciated that the invention is not restricted in itsapplicability to the two-position, two-way screw-in valve type, but thatit is applicable to all valves of the kind in which the valve cone, inthe closed position, engages an annular ridge constituting a valve seat.

What is claimed is:
 1. A pressure compensated high pressure valve,comprising:means forming a valve housing having an elongate recesstherein; valve seat means positioned within said elongate recess andcomprising an annular ridge made of steel; valve spindle means providedwith integral valve head means comprising a substantially conicalsurface adapted in the closed condition of said valve to engage saidannular ridge, said valve spindle means, said valve head means and saidsurface being made of aluminum; and means for moving said conicalsurface into and out of engagement with said annular ridge.
 2. The highpressure valve of claim 1, wherein said moving means comprises meansengaging said valve spindle means for selectively moving said conicalsurface out of engagement with said annular ridge and spring means forbiasing said conical surface into engagement with said annular ridge. 3.The high pressure valve of claim 2, wherein said valve spindle meansextends through said annular ridge and wherein said valve head means islocated on one side of said annular ridge and said moving means islocated on an opposite side of said annular ridge.
 4. The high pressurevalve of claim 3, wherein said elongate recess comprises an opening in aplane parallel to said annular ridge and said valve head means isprovided between said opening and said annular ridge.
 5. The highpressure valve of claim 4, wherein said valve housing comprises at leastone radial bore extending into said elongate recess on the side of saidannular ridge opposite said valve head means.
 6. The high pressure valveof claim 5, wherein said frustro-conical surface is deformed intoconforming relationship with said annular ridge thereby to form aneffective seal when in engagement therewith.
 7. The high pressure valveof claim 6, wherein said valve housing comprises a plurality of axiallyaligned housing portions threadedly connected to each other.
 8. The highpressure valve of claim 4, wherein said elongate recess comprisescounterpressure chamber means connected to said opening by conduit meansextending through said valve spindle means.